Steel Delivery Conditions: What Do +AR, +N, +A and +QT Mean?

Steel delivery condition defines the production or heat treatment condition in which the material is supplied to the customer. Suffixes such as +AR, +N, +A and +QT are used to indicate this information. They should be read together with the steel grade, as the same grade may exhibit different machining and application characteristics under different delivery conditions. For this reason, specifying only the steel grade in an order may be insufficient. Ensuring that the technical drawing, production plan and purchase specification all refer to the same delivery condition is important for machine setup and subsequent heat treatment operations.

Common Steel Delivery Condition Codes

The delivery condition codes most commonly encountered in purchase orders and material certificates include:

This table is intended as a general reading guide. The exact scope and applicability of each code should be verified against the relevant product standard. For example, Ovako’s 25CrMo4 data sheet lists several delivery conditions separately for the same steel grade.

Why Is the Steel Grade Alone Not Enough?

The steel grade is the basis of material selection, but the delivery condition, product form and section size must also be considered. When using mechanical property values from a manufacturer’s data sheet, it is important to check the condition and size range to which the values apply.

For example, it would be incorrect to combine hardness information for an annealed material with the tensile strength of the same grade in the quenched and tempered condition as if a single product simultaneously provided all of these properties. Each row of technical data should be evaluated within its specified conditions.

Does +QT Provide the Same Properties at Every Diameter?

No. Required mechanical properties must be checked according to the section size and applicable product standard. A manufacturer’s 42CrMo4 data sheet, for example, demonstrates why the relationship between heat treatment response and section size is important.

A result specified for one diameter should not be directly applied to another section size. Particularly for larger sections, measuring only the surface hardness should not be used to conclude that the entire cross-section has identical properties. The required tests, specimen locations and acceptance criteria should be defined according to the applicable specifications.

How Does the Delivery Condition Affect the Production Plan?

The condition in which the material is supplied affects both machining operations and the sequence of subsequent heat treatment processes. A tooling and machining setup developed for annealed material may not provide the same results when the steel is supplied at a different hardness.

Cutting parameters should therefore be selected according to the actual material condition. If heat treatment will be performed later, its effects on dimensions, surface condition and machining allowance should also be considered. For further information, you can refer to our steel heat treatment guide and our article on quenched and tempered steels.

Do Not Confuse Surface Processing with Delivery Condition

Terms such as “ground,” “peeled” or “cold drawn” provide information about how the product has been processed. A code such as +A or +QT, however, describes a different technical characteristic. The heat treatment condition of a product cannot be determined simply from its appearance.

For this reason, the following three pieces of information should be specified separately in the purchase order:

• Steel grade: For example, 42CrMo4 and the applicable standard
• Delivery condition: For example, +A or +QT
• Surface or finishing process: For example, cold drawn, peeled or ground

If the supplier proposes an alternative delivery condition, its effects on the production process and required properties should be technically evaluated before acceptance.

Final Step in Document Verification

Match the documentation and label information of the delivered product with the purchase order. Do not confuse typical values in a technical data sheet with measured batch-specific results or minimum requirements specified in the contract.

If a delivery condition code is unclear, obtain clarification before starting production.

Conclusion

Steel delivery condition is an order specification that is just as important as the steel grade itself. Codes such as +AR, +N, +A and +QT indicate different production or heat treatment conditions that can affect machining and application performance. For this reason, the steel grade, delivery condition and surface processing method should be specified separately in the purchase order and verified against the relevant documentation.

To evaluate the required steel grade and delivery condition together, you can send your technical requirements to Uyar Steel through our contact page.